The verb has several distinct meanings, one of which (1)–to misbehave–is American in origin. Distinctly British (2), on the other hand, is the sense it was used in the 1939 propaganda poster “Keep Calm and Carry On”–that is, to persist in the face of obstacles. The Oxford English Dictionary tells us this originated as a nautical variation on “stay the course.” The OED quotes a 1909 newspaper (which was partial to quotation marks): “‘Carry on!’ is a word they have in the Navy. It is the ‘great word’ of the Service.‥ To-morrow the workaday life of the Fleet begins again, and the word will be, ‘Carry on!’” Familiar on both sides of the Atlantic, I reckon, is the notion (3) of carrying on, or maintaining, a legacy or tradition.
The NOOB is a fourth carry on meaning, more or less, to continue: either as an auxiliary verb (Please carry on working) or by itself (Carry on with your work). The American vernacular equivalent is keep on; Bob Dylan sings of a time when “All I knew how to do was to keep on keepin’ on.” British movie comedy Carry On Sergeant (1958) and its twenty-eight sequels cleverly packed meanings 1, 2 and 4 into the title.
In recent years, Americans have grown mighty partial to carry on 4. I’m spoiled for choice for examples and will just cite today’s (Columbia) Missourian, where a columnist writes, “these people have such a high opinion of themselves that I wasn’t certain we would be allowed to carry on with the rest of our lives without their permission.”
I am also picking up intriguing signals that meaning 3, the stiff upper lip deal, is getting some traction on these shores. Yesterday’s Washington Post had the headline: “Occupy DC Protesters Vow to Carry On Despite Camping Regulations.” And in a profile of runner Michael Pistorius in the 18 January 2012 New York Times, Michael Sokolove writes, “Some of the equipment is clamped to an exterior wall of the garage, opposite an uncovered patio; when it rains, athletes just carry on and get soaked.”
Now carry on.
notoneoffbritishisms.com 
Another variation is “Keep on Keepin’ on” –
lyrics by the Allman Brothers Band, 1980
Maybe “spoilt for choice” would be better as it’s the form more often used in England – e.g. spoilt brat / child, since I think you’re trying to give these posts an English flavour…?
Isn’t “carry on” a military expression – that is, US military? If an officer enters a work area, the enlisted personnel come to attention. The officer says “carry on,” meaning to go back to their work. I’m sure I’ve heard this commonly used in US military settings, and the meaning seems very similar to your carry on (4) and metaphorically to (2), since the enlisted personnel will continue with their work as though the “obstacle” officer were not present. Even if the current popularity of “carry on” in the US is the result of British influence, perhaps it is flourishing because there was an existing familiarity with the phrase from military usage.
Is not the expression there, ‘at ease?’
There is a fourth meaning for “carry on” – a noun – and that is to describe some comic or calamitous event – also covered by “what a to-do”.or fiasco.
Example: bull running amok in a china shop – What a carry on!:- or – A right/real/proper carry on.
The Carry On films, were then “a right Carry On” – although the title encompassed the other meanings too.
My wife, Gigi Simeone, points out: “You missed the most famous recent popularizer of this – Tim Gunn on “Project Runway.” After giving his critique or asking questions mid-way through the projects, he would leave each “designer” saying, “Carry on.”
No one has mentioned that dreadful (IMHO) 70s song by the American group Kansas! http://en.wikipedia.org/wiki/Carry_On_Wayward_Son
Not to mention Crosby Stills and Nash’s 1970 number, which was quite simply titled “Carry On.” I am tempted to conclude, “Kari, on.”
Another British usage of ‘carry on’:
While her husband was away, she was carrying on with the man next door….
(What a carry on!)
Joseph Conrad, in his book The Mirror of the Sea, uses the expression carry on to mean to continue carrying full sail, particularly when the wind was increasing. This could be risky; the faster the ship, the more voyages and more profit it could make, but it could also overstrain the vessel and bring down the masts. So a carry on could be lively and tense, the ship racing along with all its rigging taut.